The present invention relates to catalytic cracking, and more specifically to catalytic cracking compositions and processes that may be used to catalytically convert high molecular weight feedstocks into valuable lower molecular weight products having reduced sulfur content.
It is generally known that catalytic cracking catalysts which comprise zeolites such as synthetic faujasite, zeolite Beta, and ZSM-5 dispersed in an inorganic oxide matrix such as silica/alumina hydrogel, sols and clay may be used to economically convert heavy hydrocarbon feedstocks such as gas-oils and/or resid into gasoline and diesel fuel.
More recently it has been disclosed that the addition of SOx reduction "additives" such as alumina, magnesium aluminate (spinel) to cracking catalyst compositions will improve the overall performance of tile catalyst, particularly when used to process feedstocks that contain significant quantities of sulfur.
Canadian patent 1,117,511 describes FCC catalysts which contain free alumina hydrate, particularly alpha-alumina hydrate (boehmite) which may be used to catalytically crack hydrocarbons that contain sulfur.
U.S. Pat. No. 4,010,116 discloses FCC catalysts which contain pseudo-boehmite aluminas that may contain crystalline trihydrate components such as bayerite and gibbsite.
While it is recognized that additives including aluminas and spinels may be added to catalytic cracking catalysts to reduce SOx emissions during the oxidation and regeneration of FCC catalyst, the industry has not developed catalytic cracking catalyst compositions that reduce the sulfur level of cracked products such as gasoline and diesel fuel